This invention relates to cargo air bags and, more particularly, to an inflation valve and inflator combination for inflating cargo air bags with compressed air.
Cargo air bags are known to the art as a simple, low cost means of bracing railcars, trailers, and overseas containers for securing cargo for shipment. Air bags typically comprise an inflatable bladder which is secured inside a paper bag or envelope. The bags are of such a size that they can be inserted into voids between spaced loads or between the load and the side or end walls of a container such as a railroad car or trailer and then inflated to expand and secure the load against movement during transit. To this end, the air bag is provided with an inflation valve permitting the bag to be inflated in place with gas under pressure, typically compressed air, to a desired inflation pressure at which the bag is expanded to exert an outward pressure to force the load against side or end walls, or against bulkheads, to restrain the load from moving.
One such inflation valve now in use includes a plastic valve having a tubular valve body to which a flange is attached. The flange is welded to a plastic bladder inside the paper bag to form an airtight seal and the valve body extends out of the bag where it can be grasped by a suitable inflation fixture. The valve includes a valve stem mounted in the tubular body movable between a valve open position and a valve closed position sealing the bladder. The valve stem is spring loaded so that it is biased to the valve closed position until contacted by the air inflation device which pushes the valve stem inwardly to open the valve body for flow of compressed air into the bladder. That is, in such an inflation valve, the valve stem is spring loaded in the valve body and includes a closure plate at one end thereof interior of the bladder which seats against a resilient valve seat in the valve closed position. The valve body is adapted to be received in the air inflation fixture which includes an internal element for moving the valve stem against the spring biasing force and thereby moving the closure plate from its sealing position on the resilient valve seat. However, a significant problem often accompanies such an inflation valve design. Cargo air bags are typically flat in the uninflated condition and thereby lend themselves to being lain flat on a trailer or railcar floor or loading dock with the inflation valve body facing upwardly. When the air inflation fixture is placed on the valve body in an attempt to make the connection for inflating the bag, the force exerted by the operator on the fixture presses against the valve stem which causes the closure plate to press against the opposite side of the air bag and in turn against the floor. Thus, the more force that is exerted by the operator to cause the air inflation fixture to mate with the inflation valve, the more force that is exerted against the closure plate causing the closure plate to remain sealed against the valve seat in the valve closed position. This is directly counter to the desired result of moving the closure plate off of its seated position to open the valve for inflation of the air bag.